Image-based virtual reality is emerging as a major alternative to the more traditional 3D-based virtual reality (VR) environment. Unlike the virtual environment generated by 3D graphics, in which the information to represent the environment is kept internally as geometry and texture maps, an image-based VR environment represents the environment by one or more images, which can be either captured by camera or synthesized from 3D computer graphics.
There are two phases in creating VR environments, the authoring phase and the run time phase. The authoring phase is the process of providing an accurate representation of the VR environment. The runtime phase is directed to providing that representation on the computer display. The present invention is directed toward the authoring phase of creating a VR environment.
There are two types of image-based VR representations: the single-node 2D representation, which represents the world around one nodal point by a panorama, and the light-field 4D representation, which represents the world contained in a pre-defined 3D volume. The main advantages of the image-based VR are its simplicity for rendering (i.e., no complicated 3D real-time rendering), its photographic quality realism, and the 3D illusion experienced by users even though no geometric information is available.
The present invention is related to the problem in creating contents for single-node 2D panoramas. The conventional way to create a surrounding panorama is by rotating a camera around its nodal point. Utilizing a 15 mm rectilinear lens with 35 mm film, it takes as many as 12 pictures to capture a panorama with 90-degree vertical field of view. Capturing a full spherical panorama requires at even more pictures and involves rotating the camera along two different axes. In addition, the image registration process becomes complicated.
Fortunately, commercial fisheye lenses exist, which produce very high quality pictures with a near 180-degree field of view, i.e., a hemisphere or an even larger field of view. Accordingly, utilizing a fisheye lens 2 to 4 pictures can be taken to provide a full 360 degree field of view. It is desirable to use such a fisheye lens to capture the spherical panorama to minimize the number of pictures that have to be taken.
The problem with utilizing a fisheye lens is that they are not easily "stitched" together utilizing conventional techniques. That is, accurately registering the fisheye images is complicated utilizing traditional techniques. In addition, heretofore elaborate calibration equipment for the fisheye lens is required to calibrate traditional fisheye lens. Elaborate calibration techniques prohibitively increase the overall costs and are available to only the most sophisticated VR environments.
Accordingly, what is needed is a method and system for creating a VR environment which overcomes the problems associated creating a 3D VR environment. The present invention addresses such a need.